This invention relates in general to video display monitor support structures and is particularly directed to an arrangement for stably positioning a display monitor over a wide range of tilt angles and rotational orientations.
Because of the high degree of interaction between a display monitor and its user in such applications as computer terminals, word processors, communications systems, and video monitoring equipment, the human factors considerations engineered into the display monitor are of the utmost importance, particularly to the user. Such parameters as video display sweep rates, background color and contrast, and the general viewability of the information presented on the display monitor, which generally includes a cathode ray tube (CRT), all affect the quality of video information provided to the user and the ability of the user to utilize the thus displayed information.
In the general area of display monitor viewability, human factors engineering has been primarily concerned with improving the presentation of video information with minimum user inconvenience and hardship. A prime consideration has been directed toward the reduction of glare on the faceplate of the display monitor and achieving and maintaining optimum viewing angles relative to the display monitor. Efforts in these areas to improve the presentation of the video information on the display monitor have been primarily directed to the design and use of various display monitor positioning and tilt mechanisms for minimizing glare while optimizing user viewing angle with minimal inconvenience and adjustment of display monitor orientation.
Various approaches have been used in the prior art to selectively adjust the tilt angle of a display monitor. For example, a rotatable friction cam positioned beneath an aft portion of the video display has been used for the selective vertical displacement thereof in providing the desired tilt angle. Another approach makes use of the combination of a convex lower portion of a display platform and a concave portion of a support stand. The convex portion is inserted within the concave portion in a complementary manner and retained therein by means of a spring-loaded wing nut positioned within a longitudinal slot in a friction plate. By displacing the wing nut-spring combination along the longitudinal slot, the convex and concave surfaces are displaced relative to one another and the platform upon which the display monitor is positioned may be tilted as desired. Other approaches involve various complicated arrangements of bellows, flexible members, etc., in combination with various coupled combinations of support links.
One specific prior art approach is disclosed in U.S. Pat. No. 3,789,140 to McQueen et al wherein is described an arrangement for manually tilting the primary image screen of a CRT about a horizontal axis disposed slightly behind the screen by means of a hand wheel exposed through a cabinet enclosing the CRT utilizing a friction pivot on a lateral portion of the CRT. Another approach to a friction pivot-type of CRT tilt arrangement is disclosed in U.S. Pat. No. 4,372,515 to Noonan which provides fore and aft retention by means of a spur gear on an upper support unit and a rack gear on a lower support unit which act to co-locate the origin of the arc of a rocker, the center of gravity, and the origin of the arc of the pitch diameter of the spur gear of the display unit through the tilt range. U.S. Pat. No. 4,410,159 to McVicker et al discloses yet another approach involving a molded base element having a pair of concave tracks in the top and an annular recess in the bottom wherein the concave tracks receive and support a molded cradle element adapted to contain and support a CRT. The annular recess receives an annular support ring adapted to support the base and the cradle with the three assembled CRT support elements maintained in contact with each other by gravity and provided with keepers to maintain assembly of the aforementioned components. The aforementioned cross-referenced patent application provides display monitor tilt control over a wide range of tilt angles, but no rotational displacement of the monitor is afforded.
The present invention represents an improvement over the prior art in that it provides a low cost, reliable, and easily adjusted rotating tilt arrangement for stably positioning a display monitor at a selected tilt angle and in a given viewing direction by directly orienting the display monitor as desired. Once properly positioned, the display monitor remains in that orientation until manually displaced. Counterbalancing moments permit display monitor orientation to be changed with a minimal amount of applied force.